A novel base-mediated intramolecular hydroamination to build fused heteroaryl pyrazinones

Abstract Functionalized fused heteroaryl pyrazinones were built up through a novel DBU-catalyzed intramolecular hydroamination reaction of aryl(prop-2-yn-1-yl)-1 H -heteroaryl-2-carboxamides. The nucleophilic addition afforded three isomers; two with an exo -cyclic double bond [cis ( Z ), trans ( E )], and a third one with an endo -cyclic double bond. After the carboxamide deprotection, isomerization of the mixture under acidic conditions resulted in a unique isomer.